Method and appartus for forming a filter rod

ABSTRACT

The present invention provides a method of forming a filter rod (R) of separated fibres and/or randomly oriented filter material fibres (F) for the tobacco processing industry, the method comprising: supplying separated filter material fibres (F) to an inlet (I) of a conveyor device ( 2 ), conveying the separated filter material fibres (F) along a process path (P) in a conveying direction (D) from the inlet (I) to an outlet (O) of the conveyor device ( 2 ), whereby a strand ( 4 ) of the filter material fibres (F) is formed along the process path (P), introducing at least one additive (A), especially a binder, to the strand ( 4 ) of filter material fibres (F) on the process path (P) in the conveyor device ( 2 ) at a position that is closer to the outlet (O) than the inlet (I), and consolidating the filter material fibres (F) into a filter rod (R) by wrapping the strand ( 4 ) of filter material fibres (F) with a wrapper material ( 6 ) after the strand ( 4 ) exits the outlet (O) of the conveyor device ( 2 ) in the conveying direction (D). Desirably, the at least one additive (A) is introduced or applied to the strand ( 4 ) of filter material fibres (F) proximate or adjacent to the outlet (O) of the conveyor device ( 2 ). The invention also provides an apparatus ( 1 ) for forming such a filter rod (R) of separated and/or randomly oriented filter material fibres (F).

The present invention relates to a method and apparatus for producing a filter rod of filter material fibres, especially separated fibres, for the tobacco industry. In particular, the invention relates to a method and apparatus for forming filter rods comprised of individual or separated fibres, such as randomly-oriented fibres.

Conventional filters for smoking articles, such as cigarettes and cigarillos and the like, typically comprise at least one substantially cylindrical segment of cellulose acetate fibres mixed with a plasticizer, such as triacetin. The cellulose acetate fibres come as continuous tow packed in a bale format which is then processed in a continuous bundle and sprayed with triacetin. In this process, the cellulose acetate fibres are formed into a continuous filter rod which is wrapped in a paper-based wrapper and then cut to create individual filter segments. During formation of the filter rod, different compounds can be added to the cellulose acetate to provide the filter rod with specific properties. For example, the compounds may include adsorbents or flavours and may be provided in a particulate form, liquid form, or solid form. A filter for a smoking article may then be made of one segment of a filter rod, or from multiple segments of the same or of different filter rod compositions assembled together with at least one wrapping. The multiple segments may or may not be arranged with cavities or spaces between them.

It has also been proposed to manufacture filters comprising a non-woven filter material, such as randomly oriented fibres. Such filters essentially comprise a rod of compacted filter material fibres, such as acetate and/or polyethylene fibres, preferably non-plasticized. Such filters can provide improved filtration efficiency compared to conventional plasticized cellulose acetate, in particular for smoking articles having a reduced length and/or a reduced circumference compared to standard or so-called “King size” smoking articles which have a length of about 68 to 72 mm and a circumference of about 23 to 25 mm.

One drawback of filters fabricated from separated or randomly oriented fibres for the tobacco industry, however, is that they are more difficult to manufacture than the conventional filters of plasticized cellulose acetate fibres due to the difficulty of controlling the volume or amount of fibres and any additives in single filter segments. Indeed, in contrast to filter segments cut from plasticized cellulose acetate tow filter rods, the segments cut from filter rods of separated and/or randomly oriented fibres typically do not sustain or provide a reliable and regular shape at their cut ends, where the fibres and the additives may have a tendency to ravel out, tatter, or fray. This makes it very difficult to control consistency and reproducibility of the filter segments, not to mention their combination with other segments to form a smoking article filter.

Some methods or techniques and arrangements for manufacturing smoking article filters from randomly oriented fibres have been described in the prior art, for example in U.S. Pat. No. 7,318,797 and EP 2 641 484. The techniques and arrangements described in these documents particularly focus on the handling of the filter material fibres in a fluidized bed to allow formation of a filter rod of separated and/or randomly oriented fibres using a suction belt of a suction conveyor, similar to those used in tobacco rod production. However, they do not address the problem of controlling the structure of the filter rods to allow proper cutting and/or combination of filter segments to form final smoking article filters.

Although use of a plasticizer with randomly oriented fibres might be contemplated, the application of such plasticizers onto the fibres is typically by spraying and this would lead to a substantial contamination of the conventional filter rod manufacturing equipment, potentially causing damage to parts thereof.

An object of the present invention is therefore to provide an improved method and apparatus for forming a filter rod which addresses the above problems. In particular, the invention provides a method and apparatus for forming a filter rod from separated and/or randomly oriented filter material fibres, as opposed to conventional plasticized cellulose acetate tow.

In accordance with the present invention, a method of forming a filter rod of filter material fibres, especially separated and/or randomly oriented fibres, for the tobacco processing industry having the features set out in claim 1 is provided. The invention also provides an apparatus for forming a filter rod of filter material fibres for the tobacco processing industry as set out in claim 11. Various advantageous and/or preferred features are recited in the dependent claims.

According to one aspect, therefore, the invention provides a method of forming a filter rod from filter material fibres, especially separated fibres and/or randomly oriented fibres, for the tobacco processing industry, the method comprising:

-   -   supplying separated filter material fibres to an inlet of a         conveyor device,     -   conveying the filter material fibres along a process path in a         conveying direction from the inlet to an outlet of the conveyor         device, whereby an essentially continuous strand of the         separated filter material fibres is formed along the process         path,     -   introducing at least one additive, especially a binder, to the         strand of filter material fibres in the conveyor device at a         position along the process path that is desirably located closer         to the outlet than to the inlet, and     -   consolidating the filter material fibres into a filter rod by         wrapping the strand of filter material fibres with a wrapper         material after the strand exits the outlet of the conveyor         device in the conveying direction.

Because the separated filter material fibres are loose and/or randomly oriented fibres, it is firstly necessary to collect and form the fibres into a substantially continuous strand. This is achieved with the present invention by supplying the separated or loose fibres to a conveyor device and conveying those filter material fibres along the process path. With the present invention, at least one additive, for instance a binder, may be added to the substantially continuous strand of the filter material fibres close to an outlet of a conveyor device. This provides an efficient delivery of the fibres in a controlled and consistent manner without risking fouling or contamination of the conveyor device. Filter rods produced from separated or randomly oriented fibres typically permit a higher additive load or content when compared with conventional cellulose acetate tow filters, which can be of particular interest for manufacturing filters with improved filtration properties for gas-phase components of tobacco smoke, especially when the additive in the randomly oriented fibres comprises an adsorbent, such as activated charcoal.

In a preferred embodiment, the conveyor device is a suction conveyor device which includes one or more suction conveyor member, such as a suction belt, along the process path. The step of introducing the at least one additive to the strand preferably includes applying the additive to the strand of filter material fibres on the suction conveyor device, and in particular on the suction belt. Importantly, the use of a binder in this way is not a simple matter because of the need to apply this binder uniformly to the fibres. The fibres are typically transported in a fluidized bed before being drawn onto the suction belt of the suction conveyor device to form a filter rod (similar to the manner in which tobacco rods are produced when manufacturing a smoking article). Thus, an application of the binder to the fibres in the fluidized bed or in the suction conveyor can lead to fouling or extensive contamination of the filter rod making machinery and can make uniform application to the fibres difficult due to the air-stream in the fluidized bed and/or the under-pressure or vacuum in the suction conveyor. Rather counter-intuitively, these issues have been resolved or at least substantially ameliorated by introducing the binder to the strand of filter material fibres close to the outlet of the conveyor device.

In a preferred embodiment, the step of introducing at least one additive comprises applying the additive in a final one-third, preferably in a final one-fifth, and more preferably in a final one-tenth of the process path defined by the conveyor device; i.e. at or upstream of the outlet. In this context, it will be noted that a suction conveyor device may typically be expected to have a length in a range of about 1 metre to 3 metres.

In a particularly preferred embodiment of the invention, the step of introducing at least one additive is carried out at least proximate to or adjacent the outlet of the conveyor device before the strand of filter material fibres exits the conveyor device. The application of the additive proximate or at the outlet, and therefore just before wrapping of the fibres to form the filter rod, ensures quick or rapid contact between the binder, fibres and wrapper material providing improved binding action to the fibres and improved stability of the filter rod manufactured.

In a particularly preferred embodiment, the introduction of the at least one additive comprises applying the additive in a substantially fluid or liquid form, preferably by spraying, onto the strand of filter material fibres on the process path. In this regard, introducing the at least one additive preferably comprises applying or delivering the additive to the strand of filter material fibres via a gaseous carrier, such as compressed air or steam. The at least one additive preferably comprises one or more of: an aqueous composition, a flavouring compound, a binder compound, and a plasticizer.

The at least one additive may alternatively or additionally be provided as an encapsulated compound or material. The spraying of the additive onto the continuous strand of fibres preferably occurs at an angle in the range of 0° and 90° to the conveying direction.

In a particularly preferred embodiment, the method includes locally moderating or reducing a vacuum or under-pressure applied to the strand of filter material fibres in the conveyor device at or immediately prior to introducing the at least one additive, e.g. a binder, thereto. In the case of a suction conveyor device, this can be achieved with one or more plate member or baffle arranged on the suction belt in the process path. In this way, the filter material fibres of the strand are relaxed and the at least one additive can better penetrate the strand. Also, there are lower additive losses due to a lower vacuum strength.

In a preferred embodiment, the method of forming a filter rod further comprises heating the additive before and/or during the step of introducing the at least one additive.

In a preferred embodiment, the step of supplying the filter material fibres to the inlet of the conveyor device includes delivering a mixture of filter material fibres (for example, of different fibres) to the inlet of the conveyor device. At least one particulate material may optionally be supplied to the inlet of the conveyor device together with the filter material fibres.

According to another aspect, the present invention provides an apparatus for forming a filter rod from separated filter material fibres for the tobacco processing industry, the apparatus comprising:

-   -   a conveyor device having a conveyor member for conveying         separated filter material fibres along a process path in a         conveying direction from an inlet to an outlet of the conveyor         device, wherein the conveyor member is configured to create a         continuous strand of filter material fibres from the separated         filter material fibres supplied to the inlet;     -   means for wrapping the continuous strand of filter material         fibres in a wrapper material after the strand exits or emerges         from an outlet of the conveyor device to form a filter rod         having a core of filter material fibres surrounded by the         wrapper material; and     -   an additive application system comprising at least one         applicator device, such as a nozzle, arranged to apply an         additive, preferably by spraying, to the strand of filter         material fibres in the conveyor device at a position along the         process path, and preferably at a position closer to an outlet         of the conveyor device than to the inlet thereof.

As noted above, in contrast to conventional cellulose acetate tow, in which the cellulose acetate tow fibres are provided as a continuous strand to a filter maker from a tow bale and are processed and compressed in the filter maker with plasticizer, the filter material fibres used in the present invention are separated and are thus provided as loose and randomly oriented fibres. Accordingly, it is first necessary to collect and arrange the separated fibres into a generally continuous strand, which is achieved via the conveyor device.

Furthermore, the apparatus of the invention advantageously provides an additive application system located close to the outlet of the conveyor device. This assists a very efficient delivery of an additive, such as a binder, to the fibres in a controlled and consistent manner without risking an undesired contamination of the conveyor device. Further, the location of the applicator device of the application system at or adjacent to the outlet, e.g. just before the wrapping means, allows application of a binder at the surface of the fibre strand just before wrapping, thereby ensuring quick contact between binder, fibres and wrapper material to provide improved binding action to the fibres and improved stability for the filter rod produced.

In a preferred embodiment, the conveyor device is a suction conveyor device and the conveyor member is a suction belt. The filter material fibres are thus typically supplied to the inlet via a vacuum or under-pressure created by and/or in the suction conveyor device. In this regard, the at least one applicator device, such as a nozzle, is desirably arranged in a final one-third, more preferably in a final one-fifth, and even more preferably in a final one-tenth of the process path defined by the conveyor device; i.e. at or upstream of the outlet. In this context, it will be noted that the conveyor device may typically be expected to have a length in a range of about 1 metre to about 3 metres.

In a preferred embodiment, the at least one applicator device (e.g. nozzle) of the additive application system is arranged proximate to or adjacent the outlet of the conveyor device. In this regard, the applicator device or nozzle may be arranged or oriented at an angle of between 0° and 90° to the conveyor member of the conveyor device. Thus, in a preferred embodiment, the applicator device or nozzle may be directed or arranged to extend substantially parallel to the direction of the conveyor member, preferably within a substantially horizontal plane. In another preferred example, the additive application system includes at least one second applicator device (e.g. a second nozzle), and the at least one second applicator device may be directed or may extend substantially perpendicular to a travel direction of the continuous strand in the conveyor device.

In a preferred embodiment, the additive application system of the apparatus comprises at least one carrier source and/or a reservoir or a supply of each additive. Each carrier source and/or each reservoir or supply sin fluid connection with theta least one applicator device, i.e. preferably with at least one respective nozzle. Also, the additive application system preferably includes heating means for heating the additive before or during application thereof in the conveyor device.

As noted above, in a particularly preferred embodiment, the apparatus includes one or more plate member or baffle member arranged in the conveyor device for locally moderating or reducing a vacuum or under-pressure applied to the strand of filter material fibres at or immediately upstream of the at least one applicator device or nozzle. In this manner, the filter material fibres of the strand on the suction belt can relax allowing the at least one additive to better penetrate the strand, while also reducing additive losses.

According to a further aspect, the present invention provides a filter rod which is produced by the apparatus and/or method of the invention as described with respect to any one of the embodiments above. The invention thus also provides a smoking article having a filter element cut from such a filter rod.

For a more complete understanding of the invention and the advantages thereof, exemplary embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawing figures, in which like reference characters designate like parts and in which:

FIG. 1 shows a schematic side view of an apparatus for forming a filter rod of randomly oriented fibres for the tobacco processing industry according to one particular embodiment;

FIG. 2 shows a schematic view of the apparatus in FIG. 1 in the direction of arrows B-B; and

FIG. 3 is a flow diagram that schematically illustrates a method according to a preferred embodiment.

The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments of the invention and together with the description serve to explain the principles of the invention. Other embodiments of the invention and many of the attendant advantages of the invention will be readily appreciated as they become better understood with reference to the following detailed description.

It will be appreciated that common and well understood elements that may be useful or necessary in a commercially feasible embodiment are not necessarily depicted in order to facilitate a more abstracted view of the embodiments. The elements of the drawings are not necessarily illustrated to scale relative to each other. It will further be appreciated that certain actions and/or steps in an embodiment of a method may be described or depicted in a particular order of occurrences while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used in the present specification have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study, except where specific meanings have otherwise been set forth herein.

Referring to drawing FIGS. 1 and 2, an apparatus 1 for forming a filter rod R from filter material fibres F for use in the tobacco processing industry is shown schematically. The apparatus 1 in this particular embodiment comprises a suction conveyor device 2 configured to transport or convey separated and randomly oriented filter material fibres F from a fibre supply S at an inlet I of the conveyor device 2 in a conveying direction D along a process path P to an outlet O of the conveyor device 2. The separated and randomly oriented fibres Fare supplied to the inlet I of the conveyor device 2 and may comprise a single type of fibre or alternatively a mixture of different types and optionally also a particulate material. For transporting these separated fibres F from the fibre supply S, the conveyor device 2 comprises an elongate conveyor member 3 in the form of an endless suction belt. This suction belt member 3 draws the loosely held separated and randomly oriented filter material fibres F from the supply S under the action of an under-pressure or vacuum V and carries those fibres F in the conveying direction D as the suction belt 3 is driven in its endless loop. Due to the structure and operation of the suction belt 3, the conveyor device 2 is configured to form or to produce a generally continuous strand 4 of the fibres F as it draws and conveys those fibres F along the process path from the inlet I to the outlet O. The apparatus 1 further includes a wrapping device 5 which interfaces with the conveyor device 2 at the outlet O for consolidating the continuous strand 4 of filter material fibres F by wrapping the strand 4 in at least one sheet or web of wrapping material 6, such as one or more thin sheets or webs of paper.

The apparatus 1 furthermore includes an additive application system 7 having at least one first nozzle 8 configured and arranged for applying an additive A to the strand 4 of filter material fibres F on the process path P in the conveyor device 2. Each such first nozzle 8 is arranged at a position proximate or close to the outlet O of the suction conveyor device 2 and is desirably arranged to extend or be directed in a plane approximately parallel to the conveying direction D, i.e. a substantially horizontal plane. Preferably, the additive A delivered through the first nozzle 8 is a binder composition projected in a substantially liquid form onto the fibre strand 4 on the suction belt 3 adjacent the outlet O of the conveyor device 2. In a variant, the additive A can also be a binder provided in a pulverulent form (e.g. as a powder or micro-encapsulated particles) and projected on the fibres. Such a binder may be activated by subsequently heating and/or by compacting the fibre strand 4 after it exits the conveyor device 2; for example, in the wrapping device 5 or even down-stream of the wrapping device 5 and before the continuous filter rod R is cut.

Further, the additive application system 7 includes at least one second nozzle 9 proximate the outlet O which extends or is directed approximately perpendicular to the conveying direction D, as shown in FIG. 1. This second nozzle 9 can be used to deliver the same additive A as the first nozzle 8 or a different additive, in the same or a different form. When the same additive A is delivered, each of these first and second nozzles 8, 9 is connected via a conduit or piping 10 in fluid communication with a reservoir 11, which holds the additive A to be applied to the fibres F. Advantageously, the reservoir 11, and/or the nozzles 8, 9 may include or be associated with heating means for heating the additive A such that it is easily applicable or projectable through those nozzles 8, 9, especially if the additive A is a gel and/or is viscous at room temperature (25° C.). To this end, the first and second nozzles 8, 9 are desirably also connected in fluid communication to a pressure source 12, e.g. compressed air or steam, which is configured and arranged to carry or drive the additive A from the reservoir 11 to each of the first and second nozzles 8, 9 for application, e.g. spraying, thereof onto the strand 4 of fibres F conveyed on the suction belt 3 along the process path P of the conveying device 2.

When the first and second nozzles 8, 9 are used to deliver different additives to the fibre strand 4, each of the first and second nozzles 8, 9 is then preferably connected to a separate reservoir for the respective additive by appropriate conduits or piping, with each reservoir in turn connected to a pressure source. By way of example, the first nozzle 8 may be configured and arranged to spray a binder composition onto the fibre strand 4 at or adjacent an outlet O of the conveyor device 2 and thus connected to a binder reservoir. The second nozzle 9, on the other hand, may be configured and arranged to introduce an encapsulated additive, such as a breakable capsule, from a capsule supply or reservoir (not shown) into the fibre strand 4 at regular intervals (immediately) prior to the strand exiting the conveyor device 2 to be wrapped via in wrapper device 5 to form the continuous filter rod R. The supplies or reservoirs for the binder additive and capsules may then be connected to individual pressure sources to allow application or projection thereof at appropriate pressures of the two additives from each of nozzles 8, 9.

In a preferred embodiment, a vacuum breaker (not shown in the figures) may be provided or arranged in the conveyor device 2 at the position of the first nozzle 8 and/or preferably just before that nozzle. A vacuum breaker, which may be formed of or comprise a deflection member located upstream of the first nozzle 8 in the process path P, desirably locally reduces the vacuum or under-pressure in the conveyor device 2, thereby relaxing the fibres onto the suction belt 3. This allows for a better penetration of the additive A sprayed onto the fibre strand 4 into the fibres thereof and, thus, a more homogenous blend of the fibres and additive. In addition, this further reduces a risk of contamination in the conveyor device 2 and provides enhanced control of the delivery of the additive A to the fibre strand 4.

As the fibres F in the substantially continuous strand 4 exit or emerge from the outlet O of the conveying device 2, they directly enter the wrapping device 5. The strip or web 6 of wrapping material (e.g. paper) is drawn from a bulk roll 13 and fed via rollers 14 to a position where it is below and travelling parallel to the strand 4 of fibres F emerging from the outlet O. In this way, the fibre strand 4 can be released or discharged from the suction belt 3 and deposited onto the wrapping material 6. The wrapping device 5 then consolidates the fibre strand 4 by means of the wrapping material 6 into a substantially continuous filter rod R. To assist the wrapping process, an applicator 15 may provide the strip or web 6 of paper with a localised adhesive so that the wrapping material is adhesively bonded as it is wrapped around the strand 4 of fibres F. Because the additive A is applied to the fibre strand 4 immediately or directly upstream of the wrapping device 5, that additive A may also interact with the strip or web of wrapping material to provide a uniform and reliably wrapped filter rod. If the additive A is a binder, that also ensures that the randomly oriented fibres F of the filter material do not ravel or fray when the filter rod R is later cut to form individual filter segments for smoking articles.

Referring now to FIG. 3 of the drawings, a flow diagram is shown that schematically illustrates the steps in a method of forming a filter rod R of filter material fibres F according to the embodiment of the invention described above with respect to FIGS. 1 and 2. In this regard, the first box I of FIG. 3 represents the step of supplying the filter material fibres F to the inlet I of the conveyor device 2, e.g. via a fluidised bed (not shown). The second box II then represents the step of conveying the filter material fibres F along a process path in a conveying direction D from the inlet I to an outlet O of the conveyor device 2, whereby a substantially continuous strand 4 of the filter material fibres F is formed along the process path defined by the conveyor device 2. The third box III represents the step of introducing at least one additive A, especially a binder, to the strand 4 of filter material fibres F in the conveyor device 2 at a position in the process path P closer to the outlet O than the inlet I. The final box IV in FIG. 3 of the drawings represents the step of consolidating the filter material fibres F into a filter rod R by wrapping the fibre strand 4 with a wrapper material 6 after the strand 4 exits the outlet O of the conveyor device 2 in the conveying direction D.

Although specific embodiments of the invention have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternative and/or equivalent implementations exist. In this regard, it will be appreciated that the exemplary embodiment or exemplary embodiments are examples and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

Also, it will be appreciated that in this document, the terms “comprise”, “comprising”, “include”, “including”, “contain”, “containing”, “have”, “having”, and any variations thereof, are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus or system described herein is not limited to those features or parts or elements or steps recited but may include other elements, features, parts or steps not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the terms “a” and “an” used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. Moreover, the terms “first”, “second”, “third”, etc. are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects.

LIST OF REFERENCE SIGNS

-   1 apparatus -   2 conveyor device -   3 conveyor member or suction belt -   4 strand of fibres -   5 wrapping device -   6 strip or web of wrapper material -   7 additive application system -   8 first nozzle -   9 second nozzle -   10 conduit or piping -   11 reservoir -   12 pressure source -   13 bulk roll -   14 roller -   15 adhesive applicator -   F filter material fibres -   R filter rod -   S fibre supply -   V vacuum or under-pressure -   P process pathin the conveyor device -   D conveying direction -   I inlet of the conveyor device -   O outlet of the conveyor device -   A additive 

1. A method of forming a filter rod of separated filter material fibres for the tobacco processing industry, the method comprising: supplying separated filter material fibres to an inlet of a conveyor device, conveying the filter material fibres along a process path in a conveying direction from the inlet to an outlet of the conveyor device, whereby a strand of the filter material fibres is formed along the process path, introducing at least one additive to the strand of filter material fibres on the process path in the conveyor device at a position closer to the outlet than to the inlet, and consolidating the filter material fibres into a filter rod by wrapping the strand of filter material fibres with a wrapper material after the strand exits the outlet of the conveyor device in the conveying direction.
 2. A method according to claim 1, wherein the at least one additive is applied to the strand of filter material fibres at or proximate to the outlet of the conveyor device.
 3. A method according to claim 1, wherein the conveyor device is a suction conveyor device comprising one or more suction members along the process path, wherein the step of introducing the at least one additive to the strand includes applying the additive to the strand of filter material fibres on the suction conveyor device.
 4. A method according to any of claim 1, wherein the step of introducing at least one additive is carried out within a final one-third of the process path defined by the conveyor device before the strand of filter material fibres exits the conveyor device.
 5. A method according to any of claim 1, wherein: the step of introducing at least one additive comprises applying the additive in a substantially fluid or liquid form by spraying, onto the strand of filter material fibres on the process path; and wherein the additive is sprayed onto the strand at an angle of between 0° and 90° to the conveying direction.
 6. A method according to any of claim 1, further comprising locally moderating or reducing a vacuum or an under-pressure applied to the strand of filter material fibres in the conveyor device at or immediately prior to introducing the at least one additive thereto.
 7. A method according to claim 1, further comprising heating the additive before and/or during the step of introducing the at least one additive.
 8. A method according to any of claim 1, wherein the at least one additive comprises one or more of: an aqueous composition, a flavouring composition, a binder composition, a plasticizer, and an encapsulated compound or material.
 9. A method according to any of claim 1, wherein the step of introducing at least one additive comprises applying or delivering the additive to the strand of filter material fibres via a gaseous carrier, preferably compressed air or steam.
 10. A method according to any of claim 1, wherein the step of supplying the separated filter material fibres to the inlet of the conveyor device includes delivering a mixture of (e.g. different) loose, randomly oriented filter material fibres and optionally at least one particulate material to the inlet.
 11. An apparatus for forming a filter rod from separated filter material fibres for the tobacco processing industry, comprising: a conveyor device having a conveyor member for conveying separated filter material fibres along a process path in a conveying direction from an inlet to an outlet of the conveyor device, wherein the conveyor member is configured to create a continuous strand of filter material fibres from the separated filter material fibres supplied to the inlet; a wrapping device for wrapping the continuous strand of filter material fibres in a wrapper material after the strand exits or emerges from an outlet of the conveyor device thereby to form a filter rod having a core of filter material fibres surrounded by the wrapper material; and an additive application system comprising at least one applicator device, such as a nozzle, configured and arranged to apply an additive, especially a binder, to the strand of fibres at a position on the process path in the conveyor device closer to the outlet than the inlet.
 12. An apparatus according to claim 11, wherein: the at least one applicator device is configured and arranged to apply the additive by spraying at a position proximate or adjacent to the outlet of the conveyor device; and/or wherein the conveyor device is a suction conveyor device and the conveyor member is a suction belt, wherein the filter material fibres are supplied to the inlet by an under-pressure or vacuum created by and/or in the suction conveyor device.
 13. An apparatus according to claim 11, wherein: the at least one applicator device includes a nozzle arranged or oriented at an angle of between 0° and 90° to the direction of the conveyor device; and/or the nozzle is directed or extends substantially parallel to the direction of the conveyor member, preferably within a substantially horizontal plane; and/or the nozzle is directed or extends substantially perpendicular to the conveying direction.
 14. An apparatus according to claim 11, wherein the additive application system comprises at least one supply or reservoir for each additive and optionally a carrier source, wherein each carrier source and each supply or reservoir is connected to said at least one applicator device, and preferably to each nozzle.
 15. An apparatus according to any of claim 10, further comprising one or more plate member in the conveyor device for locally moderating or reducing a vacuum or an under-pressure applied to the strand of filter material fibres at or immediately upstream of the at least one applicator device or nozzle; and/or wherein the additive application system comprises heating means for heating the additive before or during application in the conveyor device.
 16. The method according to claim 3, wherein the at least one suction device includes a suction belt.
 17. The method according to claim 4, wherein the step of introducing at least one additive is carried out within a final one-fifth of the process path.
 18. The method according to claim 17, wherein the step of introducing at least one additive is carried out within a final one-tenth of the process path. 